Electrical interconnections for semiconductor devices and methods for forming the same

ABSTRACT

An electrical interconnection includes a wire loop having a first end bonded to a first bonding site using a first bonding portion, and a second end bonded to a second bonding site using a second bonding portion. The second bonding portion includes a folded portion having a wire that extends from the second end of the wire loop and is folded on the second bonding site. The folded portion includes a first folded portion connected to the second end of the wire loop and extending toward the first bonding site, a second folded portion provided on the first folded portion, and a tail protruding from a portion of the second folded portion. An interface is formed between the first and second folded portions. A top surface of the second folded portion includes an inclined surface recessed toward the first folded portion.

CROSS-REFERENCE TO RELATED APPLICATION

This U.S. non-provisional patent application claims priority under 35U.S.C. §119 to Korean Patent Application No. 10-2015-0181143, filed onDec. 17, 2015, in the Korean Intellectual Property Office, thedisclosure of which is hereby incorporated by reference in its entirety.

BACKGROUND

Embodiments of the inventive concepts relate to a semiconductor and,more particularly, to improved electrical interconnections forsemiconductor devices and methods for forming the same.

There are various techniques for electrically connecting a bonding pador lead of a semiconductor device to a bonding pad or lead of anelectronic device (e.g., a semiconductor device, a printed circuitboard, or an interposer). A wire bonding technique is widely used as oneof these techniques. The strength of the connection or the adhesiveforce of the bonding wire to the bonding pad may greatly affectelectrical and mechanical durability of semiconductor products.

SUMMARY

Embodiments of the inventive concepts may provide improved electricalinterconnections for semiconductor devices and methods for forming thesame.

Embodiments of the inventive concepts may also provide electricalinterconnections for semiconductor devices, of which an adhesive forceis improved or strengthened, along with methods of forming the same.

In an aspect, an electrical interconnection for a semiconductor devicemay include a wire loop having a first end bonded to a first bondingsite using a first bonding portion and a second end bonded to a secondbonding site using a second bonding portion. The second bonding portionmay include a folded portion having a wire that extends from the secondend of the wire loop and is folded onto the second bonding site. Thefolded portion may include a first folded portion connected to thesecond end of the wire loop which extends toward the first bonding site,a second folded portion extending from the first folded portion andprovided on the first folded portion, and a tail end protruding from anend portion of the second folded portion. A bottom surface of the secondfolded portion may be in contact with the first folded portion to forman interface between the first and second folded portions. A top surfaceof the second folded portion may be recessed toward the first foldedportion.

In an aspect, a method of forming an electrical interconnection for asemiconductor device may include performing a first bonding process byusing a bonding apparatus in which a wire is provided to connect thewire to a first bonding site, providing the wire from the bondingapparatus to a second bonding site to form a wire loop between the firstbonding site and the second bonding site, and using the bondingapparatus to perform a second bonding process on the second bonding siteto bond the wire loop to the second bonding site. Performing the secondbonding process may include moving the bonding apparatus along anoverlapping trajectory on the second bonding site to form a foldedportion on one end of the wire loop bonded to the second bonding site.The overlapping trajectory may include a first trajectory along a firstupward direction moving vertically away from the one end of the wireloop, a second trajectory moving along a first downward diagonaldirection beginning over the one end of the wire loop, movinghorizontally toward the first bonding site, and becoming verticallycloser to the second bonding site, a third trajectory moving along asecond upward direction vertically away from the one end of the wireloop, and a fourth trajectory moving along a second downward diagonaldirection beginning from nearer the first bonding site and movinghorizontally toward and vertically closer to the second bonding siteover the one end of the wire loop. In some embodiments, an overlappingstitch bond for a semiconductor device having a wire loop comprising anend bonded to a bonding site using the overlapping stitch bond, theoverlapping stitch bond comprising: a folded portion having a segmentthat extends from the end of the wire loop and is folded over the end ofthe wire loop on the bonding site.

BRIEF DESCRIPTION OF THE DRAWINGS

The inventive concepts will become more apparent in view of the attacheddrawings and accompanying detailed description.

FIGS. 1A to 1E are cross-sectional views of a semiconductor device andbonding apparatus illustrating a method of forming an electricalinterconnection for a semiconductor device, according to someembodiments of the inventive concepts.

FIGS. 2A to 2F are cross-sectional views of a semiconductor device andbonding apparatus illustrating a method of forming a stitch bondingportion of a bonding wire in an electrical interconnection according tosome embodiments of the inventive concepts.

FIG. 3A is an enlarged cross-sectional view of a portion of thesemiconductor device and bonding apparatus of FIG. 2F furtherillustrating a movement pattern of the bonding apparatus according tosome embodiments of the inventive concepts.

FIG. 3B is an enlarged cross-sectional view of a portion of thesemiconductor device and bonding apparatus of FIG. 2F furtherillustrating a movement pattern of the bonding apparatus according tosome alternative embodiments of the inventive concepts.

FIG. 4 is a cross-sectional view of a semiconductor device and bondingapparatus illustrating a method of forming an electrical interconnectionfor a semiconductor device, according to some other embodiments.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The inventive concepts will now be described more fully hereinafter withreference to the accompanying drawings, in which exemplary embodimentsof the inventive concepts are shown. The inventive concepts and methodsof achieving them will be apparent from the following exemplaryembodiments that will be described in more detail with reference to theaccompanying drawings. The embodiments of the inventive concepts may,however, be embodied in different forms and should not be constructed aslimited to the embodiments set forth herein. Rather, these embodimentsare provided so that this disclosure will be thorough and complete, andwill fully convey the scope of the inventive concept to those skilled inthe art.

Exemplary embodiments of aspects of the present inventive conceptsexplained and illustrated herein include their complementarycounterparts. The same reference numerals or the same referencedesignators denote the same elements throughout the specification.

FIGS. 1A to 1E are cross-sectional views illustrating a method offorming an electrical interconnection for a semiconductor device,according to some embodiments of the inventive concepts.

Referring to FIG. 1A, a first device 110 and a second device 120 may beprovided. The first device 110 may have a first bonding pad 115, and thesecond device 120 may have a second bonding pad 125. In someembodiments, the first device 110 may be provided on the second device120 in such a way that the second bonding pad 125 is exposed. In someembodiments, the first device 110 and the second device 120 may bevertically spaced apart from each other. In some embodiments, the firstdevice 110 and the second device 120 may be laterally spaced apart fromeach other and arranged at substantially the same level or differentlevels. In some embodiments, at least one of the first device 110 andthe second device 120 may have a lead or a lead frame instead of thebonding pad.

One of the first and second devices 110 and 120 may be a semiconductorchip, and the other of the first and second devices 110 and 120 may be aprinted circuit board or an interposer. For example, the second device120 may be the printed circuit board or the interposer, and the firstdevice 110 may be the semiconductor chip. In some embodiments, the firstdevice 110 and the second device 120 may be semiconductor chips that maybe the same as or different from each other. For example, the firstdevice 110 may be a memory chip, and the second device 120 may be alogic chip.

A bonding apparatus having a capillary 90 may be provided over a firstbonding site, e.g., the first bonding pad 115. In some embodiments, thecapillary 90 may be disposed at a level corresponding to a predeterminedheight (e.g., an electric frame-off (EFO) height) from the first bondingpad 115. A wire 95 may protrude from a central hole of the capillary 90.The wire 95 may be formed of a conductive material such as gold orcopper. An electric spark 80 may be provided to the wire 95 protrudingfrom a bottom end of the capillary 90 to melt the protruding portion(i.e., a bottom end portion) of the wire 95. Thus, a free air ball 97may be formed at the bottom end of the capillary 90. In someembodiments, ultrasonic energy or heat instead of the electric spark 80may be provided to the bottom end portion of the wire 95. Movement ofthe wire 95 within the capillary 90 may be restricted by a closingoperation of a clamp 92. As described above, the free air ball 97 may beformed at the EFO height by applying the electric spark 80.

Referring to FIG. 1B, the capillary 90 may be moved toward the firstbonding pad 115 in a state in which the clamp 92 is closed, and thus thefree air ball 97 may come in contact with the first bonding pad 115. Thefree air ball 97 may be pressed between the capillary 90 and the firstbonding pad 115. Heat and/or ultrasonic energy may be provided to thefirst device 110 to bond the free air ball 97 to the first bonding pad115. Thus, a ball bonding portion (or a first bonding portion) includingthe free air ball 97 bonded to the first bonding pad 115 may be formed.

Referring to FIG. 1C, the capillary 90 may be moved in a direction awayfrom the first bonding pad 115. At this time, the clamp 92 may be in anopened state. As the capillary 90 moves upwardly, the wire 95 may have ashape which extends from the free air ball 97 bonded to the firstbonding pad 115 in, for example, a vertical direction.

Referring to FIG. 1D, the capillary 90 raised from the first bonding pad115 may move toward a second bonding site, for example, the secondbonding pad 125. At this time, the clamp 92 may be in an opened state.Since the capillary 90 moves with the clamp 92 open, the wire 95provided from the bottom end of the capillary 90 may extend along thedirection of movement of the capillary 90. Thus, a wire loop 130 may beformed between the first bonding pad 115 and the second bonding pad 125.

Referring to FIG. 1E, the capillary 90 may be moved along an overlapping(or ribbon-shaped) trajectory Z at an end of the wire loop 130 withoutcutting the wire 95. At this time, the clamp 92 may be in an openedstate. Since the capillary 90 is moved along the overlapping trajectoryZ with the clamp 92 open, a folded portion 140 of the wire 95 may beformed at an end portion of the wire loop 130. The folded portion 140may be bonded to the second bonding pad 125. The capillary 90 may thenbe moved in a vertical direction away from the second bonding pad 125with the clamp 92 closed, and thus the wire 95 may be cut from thefolded portion 140. In some embodiments, heat and/or ultrasonic energymay be applied to the wire 95 when the wire 95 is cut from the foldedportion 140.

Thus, a stitch bonding portion (or a second bonding portion) of the wireloop 130, which is bonded to the second bonding pad 125, may be formed.The stitch bonding portion may include the folded portion 140. Thecapillary 90 may be raised to a level corresponding to an EFO height.Thereafter, a new wire bonding process may be performed using thecapillary 90, or the capillary 90 may be in a standby state. Forexample, the processes of FIGS. 1A to 1E may be repeated using thecapillary 90.

According to the present embodiment, a first end of the wire loop 130may be bonded to the first bonding pad 115 by means of the ball bondingportion (or the first bonding portion) including the free air ball 97,and a second end of the wire loop 130 may be bonded to the secondbonding pad 125 by means of the stitch bonding portion (or the secondbonding portion) including the folded portion 140. The second end of thewire loop 130 may be in contact with the second bonding pad 125.

FIGS. 2A to 2F are cross-sectional views illustrating a method offorming a stitch bonding portion of a bonding wire in an electricalinterconnection according to some embodiments of the inventive concepts.

Referring to FIG. 2A, the capillary 90 may move vertically in a firstdirection D1 away from the second bonding pad 125 with the clamp 92 open(e.g., a first rising operation). The wire 95 may extend from the wireloop 130. At this stage, the wire 95 from the capillary 90 maysubstantially vertically extend from the second bonding pad 125, and atleast a portion of wire 95 may be curved between the second bonding pad125 and the capillary 90. A process of forming a free air ball may beomitted during or before the first rising operation of the capillary 90.

Referring to FIG. 2B, the capillary 90 that has been moved along thefirst direction D1 may then be moved along a second direction D2 (e.g.,a first diagonal direction) downwardly toward the second bonding pad 125and horizontally toward first bonding pad 115 with the clamp 92 open(e.g., a first downward diagonal operation or a left downward diagonaloperation). The wire 95 may be folded at an end portion of the wire loop130, which is bonded to the second bonding pad 125.

Referring to FIG. 2C, the capillary 90 that has been moved along thesecond direction D2 may then be moved along a third direction D3vertically away from the second bonding pad 125 with the clamp 92 stillopen (e.g., a second rising operation). The wire 95 may verticallyextend from the second bonding pad 125 on the end portion of the wireloop 130.

Referring to FIG. 2D, the capillary 90 that has been moved along thethird direction D3 may then move along a fourth direction D4 (e.g., asecond diagonal direction) vertically toward the second bonding pad 125and horizontally away from first bonding pad 115 with the clamp 92 open(e.g., a second downward diagonal operation or a right downward diagonaloperation). The wire 95 may be refolded on the end portion of the wireloop 130.

Referring to FIG. 2E, the capillary 90 that has been moved along thefourth direction D4 may descend vertically toward the second bonding pad125 in a fifth direction D5. At this time, the clamp 92 may remain in anopened state. The folded portion 140 may be formed on the second bondingpad 125 by the descending capillary 90.

Referring to FIG. 2F, the capillary 90 may then be raised in a directionvertically away from the folded portion 140 with the clamp 92 open.Subsequently, the clamp 92 may be closed and the capillary 90 may beraised further such that the wire 92 is cut from the folded portion 140.Thus, the stitch bonding portion (or the second bonding portion) may beformed on the second bonding pad 125.

In the operations of the capillary 90 described above with reference toFIGS. 2A to 2D, a vertical movement distance of the capillary 90 alongthe first direction D1, the third direction D3, or each of the first andthird directions D1 and D3, may be smaller than the EFO height. In someembodiments, if the EFO height from the second or first bonding pad 125or 115 ranges from about 6,000 μm to about 7,000 μm (e.g., 6,500 μm),the vertical movement distance of the capillary 90 may range from about50 μm to about 200 μm.

A horizontal-movement distance of the capillary 90 along the seconddirection D2, the fourth direction D4, or each of the second and fourthdirections D2 and D4, may be equal to or different from the verticalmovement distance. In some embodiments, the horizontal movement distanceof the capillary 90 may range from about 30 μm to about 80 μm. At leastone of an angle between the first and second directions D1 and D2 and anangle between the third and fourth directions D3 and D4 may range fromabout 60 degrees to about 80 degrees.

FIG. 3A is an enlarged cross-sectional view of a portion of thesemiconductor device and bonding apparatus of FIG. 2F, illustrating amovement pattern of the bonding apparatus according to some embodimentsof the inventive concepts. FIG. 3B is another enlarged cross-sectionalview of a portion of the semiconductor device and bonding apparatus ofFIG. 2F illustrating a movement pattern of the bonding apparatusaccording to an alternative embodiment of the inventive concepts.

Referring to FIG. 3A, the folded portion 140 may be formed by movementof the capillary 90 along the first to fourth directions D1 to D4, i.e.,an overlapping trajectory (i.e., ribbon motion) Z of the capillary 90.Since the wire 95 is provided from the capillary 90 moving along theoverlapping (i.e., ribbon-shaped) trajectory Z, the stitch bondingportion including the folded portion 140 may be formed at one endportion of the wire loop 130.

The folded portion 140 may include a first folded portion 141 providedon the second bonding pad 125 and a second folded portion 142overlapping the first folded portion 141. An interface 143 may existbetween the first folded portion 141 and the second folded portion 142.

The first folded portion 141 may be folded at one end of the wire loop130. The first folded portion 141 may include a first end 141 aconnected to the one end of the wire loop 130 and a second end 141 bopposite to the first end 141 a. The second end 141 b may be adjacent toa portion of the wire loop 130 spaced apart from the one end thereof.The one end of the wire loop 130 may be in contact with the secondbonding pad 125. The first folded portion 141 may extend from the firstend 141 a to the second end 141 b along a surface 125 s of the secondbonding pad 125. At least a portion of the first folded portion 141 maybe in contact with the second bonding pad 125. In some embodiments, thefirst end 141 a of the first folded portion 141 may be in contact withthe surface 125 s of the second bonding pad 125, but the second end 141b of the first folded portion 141 may not be in contact with the surface125 s of the second bonding pad 125. In some embodiments, the firstfolded portion 141 may not be in contact with the surface 125 s of thesecond bonding pad 125.

The second folded portion 142 may be folded at the second end 141 b ofthe first folded portion 141. The second folded portion 142 may includea first end 142 a extending from the second end 141 b of the firstfolded portion 141 and a second end 142 b opposite to the first end 142a. The second end 142 b of the second folded portion 142 may be incontact with the first folded portion 141. The first end 142 a of thesecond folded portion 142 and the second end 141 b of the first foldedportion 141 may be connected to each other in a curved shape. The secondend 142 b of the second folded portion 142 may be provided on the firstend 141 a of the first folded portion 141 and may not be in contact withthe second bonding pad 125.

Since the wire 95 is cut from the folded portion 140, a tail end 144 mayremain on the second end 142 b of the second folded portion 142. Thetail end 144 may have a substantially spire-like shape protruding in adirection away from the second bonding pad 125. In some embodiments, atop surface of the second folded portion 142 may have an inclinedsurface 140 s recessed toward the second bonding pad 125 by the movementof the capillary 90 in the fourth direction D4 illustrated in FIG. 2Dand the descending operation of the capillary 90 in the fifth directionD5 illustrated in FIG. 2E.

A bottom surface of the second folded portion 142 may be in contact witha top surface of the first folded portion 141 to form the interface 143between the first and second folded portions 141 and 142. In someembodiments, the interface 143 may have a shape bent toward the secondbonding pad 125. In some embodiments, the interface 143 may have a flatshape. In some embodiments, the interface 143 may not extend to thesecond bonding pad 125.

In some embodiments, as illustrated in FIG. 3B, the second foldedportion 142 may further extend outside the first end 141 a of the firstfolded portion 141. The second end 142 b of the second folded portion142 may surround the first end 141 a of the first folded portion 141 andmay be in contact with the second bonding pad 125. In this case, theinterface 143 may extend to the second bonding pad 125.

The formation of the folded portion 140 of the stitch bonding portionmay be applied to the formation of the ball bonding portion. Forexample, after the free air ball 97 of FIG. 1B is bonded to the firstbonding pad 115, a folded portion may be further formed on the firstbonding pad 115 by moving the capillary 90 along an overlapping (i.e.,ribbon-shaped) trajectory such as that described above with reference toFIGS. 2A to 2E.

Alternatively, the ball bonding portion may be provided on the secondbonding pad 125, and the double-folded stitch bonding portion 140 may beprovided on the first bonding pad 115. For example, a ball bondingportion or ball 97 may be formed on the second bonding pad 125, and thewire loop 130 may extend from the ball bonding portion 97 on the secondbonding pad 125 toward the first bonding pad 115. An overlappingribbon-shaped trajectory, mirroring (or similar to) the trajectory Zdescribed previously, may then be performed to provide a double-foldedstitch bonding portion 140 on the first bonding pad 115 as shown in FIG.4.

According to some embodiments of the inventive concepts, the stitchbonding portion may include the folded portion formed by moving thecapillary along the ribbon-shaped trajectory. The folded portion mayimprove the strength of the stitch bonding portion, and thus it ispossible to prevent damage or breakage of the bonding wire which may becaused by necking. In addition, the folded portion may also improve theadhesive force of the stitch bonding portion, and thus adhesivereliability of the bonding wire may be improved when the bonding wire isused in a semiconductor or electronic device or when a bond full test isperformed. As a result, it is possible to improve electrical andmechanical durability of the semiconductor device.

As used herein, the singular terms “a”, “an”, and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be understood that when an element is referred to asbeing “connected” or “coupled” to another element, it may be directlyconnected or coupled to the other element or intervening elements may bepresent. As used herein, the term “and/or” includes any and allcombinations of one or more of the associated listed items. It will befurther understood that the terms “comprises”, “comprising”, “includes”and/or “including”, when used herein, specify the presence of statedfeatures, integers, steps, operations, elements, and/or components, butdo not preclude the presence or addition of one or more other features,integers, steps, operations, elements, components, and/or groupsthereof.

While the inventive concepts have been described with reference toexample embodiments, it will be apparent to those skilled in the artthat various changes and modifications may be made without departingfrom the spirits and scopes of the inventive concepts. Therefore, itshould be understood that the above embodiments are not limiting, butillustrative. Thus, the scopes of the inventive concepts are to bedetermined by the broadest permissible interpretation of the followingclaims and their equivalents, and shall not be restricted or limited bythe foregoing description.

What is claimed is:
 1. An electrical interconnection for a semiconductordevice, the electrical interconnection comprising: a wire loop having: afirst end bonded to a first bonding site using a first bonding portion;and a second end bonded to a second bonding site using a second bondingportion, wherein the second bonding portion comprises: a folded portionhaving a wire that extends from the second end of the wire loop and isfolded on the second bonding site, wherein the folded portion comprises:a first folded portion connected to the second end of the wire loop andextending toward the first bonding site; a second folded portionextending from the first folded portion and provided on the first foldedportion; and a tail end protruding from an end portion of the secondfolded portion, wherein a bottom surface of the second folded portion isin contact with the first folded portion to form an interfacetherebetween, and wherein a top surface of the second folded portionincludes an inclined surface recessed toward the first folded portion.2. The electrical interconnection of claim 1, wherein the first foldedportion comprises: a first end connected to the second end of the wireloop; and a second end being opposite to the first end of the firstfolded portion and facing the first end of the wire loop, wherein thefirst folded portion extends from the first end of the first foldedportion to the second end of the first folded portion along a surface ofthe second bonding site.
 3. The electrical interconnection of claim 2,wherein the second folded portion comprises: a first end extending fromthe second end of the first folded portion; and a second end beingopposite to the first end of the second folded portion and facing thefirst end of the first folded portion, wherein the first end of thesecond folded portion and the second end of the first folded portion areconnected to each other to constitute a curve-shaped end portion.
 4. Theelectrical interconnection of claim 3, wherein the second end of thesecond folded portion is provided on the first end of the first foldedportion, and wherein the interface is spaced apart from the secondbonding site.
 5. The electrical interconnection of claim 3, wherein thesecond end of the second folded portion surrounds the first end of thefirst folded portion, and wherein the interface is connected to thesecond bonding site.
 6. The electrical interconnection of claim 3,wherein the tail end protrudes from the second end of the second foldedportion in a direction away from the second bonding site.
 7. Theelectrical interconnection of claim 1, wherein the first folded portionextends from the second end of the wire loop toward the first end of thewire loop, and wherein the second folded portion extends from one end ofthe first folded portion toward the second end of the wire loop.
 8. Theelectrical interconnection of claim 1, wherein the first bonding portioncomprises: a ball provided on the first bonding site and electricallyconnected to the first bonding site, wherein the first end of the wireloop is connected to the ball, wherein the first end of the wire loop isconnected to the second end of the wire loop by a wire.
 9. Theelectrical interconnection of claim 1, wherein the first bonding siteand the second bonding site are disposed at substantially the same levelor at different levels.
 10. The electrical interconnection of claim 1,wherein the first bonding portion ball-bonded to the first bonding site;and wherein the second bonding portion stitch-bonded to the secondbonding site.
 11. A method of forming an electrical interconnection fora semiconductor device, the method comprising: performing a firstbonding process using a bonding apparatus in which a wire is provided toconnect the wire to a first bonding site; providing the wire from thebonding apparatus to a second bonding site to form a wire loop betweenthe first bonding site and the second bonding site; and performing asecond bonding process on the second bonding site using the bondingapparatus, to bond the wire loop to the second bonding site, wherein theperforming of the second bonding process comprises: moving the bondingapparatus along an overlapping trajectory on the second bonding site toform a folded portion on one end of the wire loop bonded to the secondbonding site, wherein the overlapping trajectory comprises: a firsttrajectory along a first upward direction moving vertically away fromthe one end of the wire loop; a second trajectory moving along a firstdownward diagonal direction beginning over the one end of the wire loop,moving horizontally toward the first bonding site, and becomingvertically closer to the second bonding site; a third trajectory movingalong a second upward direction vertically away from the one end of thewire loop; and a fourth trajectory moving along a second downwarddiagonal direction beginning from nearer the first bonding site andmoving horizontally toward and vertically closer to the second bondingsite over the one end of the wire loop.
 12. The method of claim 11,wherein the performing of the second bonding process further comprises:lowering the bonding apparatus toward the second bonding site aftermoving the bonding apparatus along the fourth trajectory; and raisingthe bonding apparatus from the second bonding site.
 13. The method ofclaim 11, wherein the folded portion comprises: a first folded portionconnected to the one end of the wire loop and extending toward the firstbonding site; a second folded portion extending from the first foldedportion and provided on the first folded portion; and a tail endprotruding from an end portion of the second folded portion, wherein abottom surface of the second folded portion is in contact with the firstfolded portion, and wherein a top surface of the second folded portionincludes an inclined surface recessed toward the first folded portion.14. The method of claim 13, wherein the first folded portion comprises:a first end connected to the one end of the wire loop; and a second endbeing opposite to the first end of the first folded portion and facingan opposite end of the wire loop, wherein the first folded portionextends from the first end of the first folded portion to the second endof the first folded portion along a surface of the second bonding site,and wherein the opposite end of the wire loop is bonded to the firstbonding site.
 15. The method of claim 14, wherein the second foldedportion comprises: a first end extending from the second end of thefirst folded portion; and a second end being opposite to the first endof the second folded portion and facing the first end of the firstfolded portion, wherein the first end of the second folded portion andthe second end of the first folded portion are connected to each other.16. An overlapping stitch bond for a semiconductor device having a wireloop comprising an end bonded to a bonding site using the overlappingstitch bond, the overlapping stitch bond comprising: a folded portionhaving a segment that extends from the end of the wire loop and isfolded over the end of the wire loop on the bonding site.
 17. Theoverlapping stitch bond according to claim 16, wherein the foldedportion comprises a double-folded portion having: a first folded portionconnected to the end of the wire loop and extending over the end of thewire loop; and a second folded portion extending from the first foldedportion and provided on the first folded portion.
 18. The overlappingstitch bond according to claim 17, wherein an end of the second foldedportion extends beyond the first folded portion and contacts the bondingsite.
 19. The overlapping stitch bond according to claim 17, wherein thesecond folded portion does not contact the bonding site.
 20. Theoverlapping stitch bond according to claim 19 further comprising a tailend, wherein the tail end is spaced apart from the bonding site.